Such changing arms facilitate generally the exchange of tools between a magazine of a milling machine, drilling machine or the like. They, however, can basically also be used for example to change workpieces into the work spindle of a turning lathe. The invention will be described in connection with a tool changer, however, is not to be limited thereto. The axis of rotation of the changing arm, which axis of rotation is positioned at an angle of 45.degree. with respect to the work spindle, permits thereby an arrangement of the tool magazine in such a manner that the tools are oriented at an angle of 90.degree. with respect to the work spindle and during the changing operation are swung into the direction of the work spindle.
A device of this general type is already known, in which the tools with the ends which are to be inserted into the work spindle are received pointing toward the axis of rotation of the changing arm.
Since the tools partly have very large diameters and are very long, a very large flight circle results during the change rotation of the tool arm, so that the changing arm must for this rotary movement be moved out of the machine area or the tool dimensions must be limited, in order not to collide with the machine or the chucked workpiece.
The purpose of the invention is to provide a device of this general type, which has a substantially smaller flight circle, so that the collision free space, which is to be kept free, can be substantially smaller.
The tools, which generally are received in conical tool holders, are arranged with the receiving cones pointing away from the axis of rotation, that is with the actual tool ends facing one another, in the changing arm. In order for the tools not to interfere with one another, the gripping ends of the changing arm are laterally offset such that the tool axes do not directly intersect. The outwardly pointing receiving cones have a standardized length which is designated for specific machines. The length in generally less than the largest existing tool length, so that the flight circle of the tools can be reduced through the inventive arrangement. Furthermore, because of the fixed size of the receiving cones, the collision free space, which is to be kept free, is also fixed, so that it does not need to be determined newly for each tool combination.
The lateral offset of the gripping ends of the changing arm is dimensioned such that the tools with the largest occurring diameter do not contact the axis of rotation.
In order for the changing arm to be able to insert the tools into the spindle or to remove same therefrom, it must be movable relative to the spindle in direction of the spindle axis. In some known solutions, the two arms themselves are secured swingably on the changing arm hub. However, in a preferred embodiment of the present invention, it is provided that the changing arm as a whole, that is with its support of the axis of rotation, is movable in the direction of the spindle axis, as it is actually already known. This movement can at the same time be used to pull a tool out of a tool magazine or to insert same into the tool magazine. Depending on the position of the tool magazine and depending on the position of the tools in the tool magazine, the changing arm can, however, also be designed for further movements for pulling of tools out of the magazine or for inserting of tools into the magazine.
The collision problem is of particular importance in machine tools with for example two work spindle axes, which are positioned at an angle to one another, be it that two fixedly installed spindles are provided or one spindle can be adjusted in various positions. A changing arm is provided inventively for this case, which changing arm as a whole, that is with its rotation and movement support, is pivotal additionally about a swivel axis which is aligned perpendicularly with respect to the plane which is defined by the spindle axes in an area which corresponds with the angle between the spindle axes. The changing arm can by thus pivoting about the swivel axis be adjusted to the various directions of the spindle axes. The inserting and removing movements which spatially follow the pivoting movement and the rotary movement are carried along into the various pivoting positions, so that they are available for all axial directions.
A further development of the invention provides that the changing arm as a whole is movable perpendicularly with respect to the spindle plane which is defined by the spindle axes and that it cooperates with a tool magazine which is arranged at the end of the path of movement remote from the machine. The shifting movement itself can thereby be used for inserting the tools into the tool magazine and for pulling the tools out of the tool magazine; a further advantage results when the swivel axis coincides with the axis of the tool which is aligned perpendicularly with respect to the spindle plane, since then the tool maintains its position in relationship to the magazine during the change over from one spindle axis direction to the other, so that the transfer place between changing arm and magazine remains the same for both spindle axis directions.
One exemplary embodiment of the invention provides, for supporting the changing arm, a beam which extends perpendicularly with respect to the spindle plane, a supporting block which is movable in the direction of the beam on the beam and is arranged pivotally about a swivel axis which extends perpendicularly with respect to the spindle plane, and a bearing housing which is arranged movably parallel to the spindle plane on the supporting block, in which bearing housing the axis of rotation of the changing arm is rotatably supported and in which is received a drive motor which is connected to the axis of rotation. The beam itself can thereby be pivotal about the swivel axis and can thereby take along the supporting block. A further development of the invention provides that the tool magazine itself is also pivotal about the swivel axis, so that the orientation of the magazine with respect to the changing arm is maintained during its pivoting movement.